My PBS600 belt sander stripped the teeth off the belt early in life. You can Google the belt ref no: 3M-201 (201mm is the belt length [when cut!]) and various suppliers appear.
Some are much cheaper than a supplier mentioned here!!!
(Make sure you get your belt 15mm wide!)
I found BearingsRUs were cheapest (£4.52 all incl) as they offered free [2nd Class post] delivery. (But their website didn't work properly when I went to pay). Good luck!
John Baddeley
August 2014